1. Field of the Invention
The present invention relates to a wiring thin plate applied to a flexure of a head suspension or the like and a method of manufacturing the wiring thin plate.
2. Description of Related Art
A hard disk drive incorporates hard disks that are provided so as to rotate at high speed and head suspensions with sliders that are slightly lifted from the respective hard disks to write/read data to and from the hard disks. Each head suspension has a flexure through which the slider is attached to the head suspension. The flexure includes a wiring part formed on a metal substrate. A front end of the metal substrate is provided with a tongue onto which the slider is attached.
Recent hard disks have high recording density, and therefore, the slider of the head suspension is required to make a flying height lower. In order to stabilize the low flying height, it is important to control rigidity of the metal substrate and wiring part around the tongue of the flexure.
As such a control of rigidity around a tongue of a flexure, JP06-203508A proposes a technique to thin a metal substrate of a flexure, for example.
In the case where the metal substrate is thinned, however, rigidity contribution ratio of a wiring part formed on the metal substrate relatively increases to make it difficult to control the rigidity around the tongue of the flexure.
As other means, JP09-17139A proposes a technique to specially form a planar shape of a metal substrate of a flexure and JP11-39626A proposes a technique to provide a wiring part of a flexure around a tongue with an aerial wiring portion separated from a metal substrate. These related arts, however, hardly reduce the rigidity contribution ratio of the wiring part.
Recently, as a developed technique to reduce rigidity, JP2005-322336A proposes a suspension plate with a circuit and JP2012-9111A proposes a particular flexure.
The suspension plate with the circuit of JP2005-322336A exposes at least a part of a conductive layer from a cover insulating layer at an aerial wiring portion of an outrigger. This, however, has a limit on reduction of rigidity even by partly removing the cover insulating layer because the cover insulating layer has the thickness of about 3 μm in general.
As another improvement of an aerial wiring portion, an aerial wiring portion is formed by gold-plated wiring traces only. This structure, however, tends to cause deformation of the wiring traces and vary the wiring intervals, thereby to deteriorate an electrical characteristic.
The flexure of JP2012-9111A has a thinned base insulating layer at an aerial wiring portion only. This structure, however, uses resin such as polyimide to form the base insulating layer, thins the base insulating layer by etching, and therefore involves a variation of a thickness of the thinned portion among the products.
Such a problem is occurred at not only the outrigger but also another aerial wiring portion of a tail portion of the flexure or of a part other than the flexure.